Demonstration of enhanced population feeding of the 1.53 μm emitting level of Er³⁺ in TeO₂-WO₃- Li₂O- P₂O₅ glasses using upconversion luminescence spectroscopy

P2 O5 is introduced into the Er3+ -doped tungsten tellurite glasses to speed up the I 112 4 - I 132 4 relaxation. The properties of infrared to visible upconverted luminescence as a function of P2 O5 contents are studied to demonstrate the enhanced feeding rate of the 1.53 μm emitting level of Er3+, which is in good agreement with that obtained using infrared emission spectra. The contributions of excited state absorption and cooperation energy transfer to the red and green upconverted luminescences are quantitatively evaluated. The Er3+ -doped telluride glasses containing P2 O5 could be a promising candidate as a host for broadband erbium-doped fiber amplifiers.